Locking device consisting of key and locking cylinder

Abstract

A locking device consisting of key (2) and locking cylinder (1), in particular for the actuation of electric microswitches on keyboards, telephone or the like, has a locking cylinder housing (5) and a cylinder core (11) arranged for rotation in the bore thereof and cooperating with tumblers (16). The key (2), which has a stepped-down key shaft (35) is insertable into the cylinder core which has a head plate (12), coming after a specific rotation to rest against stops of the locking cylinder housing (5). In order to obtain a simplified construction with increased security and small structural length, there is a free space between the head plate (12) of the cylinder core (11) arranged on the front side of the locking cylinder (1) and the head end (14) of the locking cylinder housing (5). Into the free space the key-shaft shoulder (37) enters, and one or more stops of the locking cylinder housing (5), are arranged at different distances from an axis of rotation of the core. The stops protrude for limiting the possible angle of rotation of the cylinder core (11) by striking a radially correspondingly widely projecting shoulder (37) of the key-shaft.

I claim: 
     
       1. A locking device having a key and locking cylinder suitable for actuation of electrical microswitches on keyboards, wherein the locking cylinder comprises a locking cylinder housing having a bore, and a cylinder bore which is arranged for rotation in said bore;   a plurality of stops disposed on said locking cylinder housing;   a plurality of platelet-shaped tumblers disposed in said cylinder core, the cylinder core having a head plate, the key having a stepped-down key shaft with a radially projecting shoulder and being insertable via said head plate into the cylinder core, said key coming after a specific rotation to rest against said stops of said locking cylinder housing;   and a free space is provided between said head plate of said cylinder core arranged on a front side of said locking cylinder and a head end of said locking cylinder housing, into which free space a key-shaft shoulder of the key can enter;   said plurality of stops of said locking cylinder housing are arranged at different distances from an axis of rotation of said cylinder core, at least one of said stops protruding for limiting an angle of rotation of said cylinder core by a striking upon the key-shaft shoulder;   said locking device further comprises a microswitch housing with grooves arranged along an interior surface of a wall of the microswitch housing facing said locking cylinder;   said locking cylinder housing has radially projecting longitudinally ribs which enter in form-locked manner into said grooves in the wall of said microswitch housing; and   said locking cylinder housing has window-shaped openings arranged axially aligned with said longitudinal ribs for passage of ends of said platelet-shaped tumblers.   
     
     
       2. A locking device according to claim 1, wherein said head end of said locking cylinder housing forms said plurality of stops; and   said plurality of stops is arranged overlapping said head plate, said head plate permitting passage of said key-shaft shoulder.   
     
     
       3. A locking device according to claim 1, wherein said key shaft is configured with a planar shaped and opposed first and second narrow longitudinal edges, said key shaft comprising a plurality of locking notches disposed on said first edge, and comprising on said second edge a step into the key-shaft shoulder.   
     
     
       4. A locking device according to claim 1, wherein said key comprises at least one profiled longitudinal groove cut into said key-shaft shoulder.   
     
     
       5. A locking device according to claim 1, further comprising a first stop projection disposed on said locking cylinder housing and a second stop projection disposed on said cylinder core head plate for limiting a range of rotation of said head plate relative to said cylinder housing.   
     
     
       6. A locking device according to claim 1, wherein said locking device is operable with said key and at least one additional key, said locking device further comprising   a non-spring-loaded pin disposed in said cylinder core for prevention of withdrawal of one of said keys in specific positions of rotation associated with individual ones of said keys.   
     
     
       7. A locking device according to claim 1, wherein said key comprises support sections on a tip of the key and in a narrow longitudinal edge region opposite said key-shaft shoulder, said longitudinal edge region extending parallel to a direction of insertion of said key; and   said cylinder bore defines a key channel having transverse flanks for engaging said support sections of said key.   
     
     
       8. A locking device according to claim 1, wherein a platelet tumbler has lateral frame arms for encircling said key, a cross section of each of said frame arms being characterized by a width and a thickness which are approximately equal.   
     
     
       9. A locking device according to claim 1, wherein there are four of said longitudinal ribs and four of said window-shaped openings arranged in equal angular distribution about a longitudinal axis of said locking cylinder.   
     
     
       10. A locking device according to claim 5, wherein a stop position of said first and said second stop projections lies in alignment with a position of angular rotation of one of said window-shaped openings;   wherein said locking device is operable with said key and at least one additional key, said locking device further comprises a non-spring-loaded pin disposed in said cylinder core and movable transversely of a rotational axis of said cylinder core for contacting the key upon insertion of the key in said cylinder core;   said cylinder housing has a plurality of entrance recesses disposed in a plane transverse to said rotation axis and coplanar with said non-spring-loaded pin for receiving said non-spring-loaded pin upon deflection of said non-spring-loaded pin by the key; and   at least one entrance recess is located coplanar with one of said longitudinal ribs in a common longitudinal plane of said locking cylinder.   
     
     
       11. A locking device according to claim 7, wherein one of said transverse flanks of said key channel is located at said head plate for support of said key shaft shoulder.